The present invention relates to a golf clubhead improved to provide the longer flight distance of a hit golf ball.
Recently, beryllium which is small in specific gravity and high in modulus of elasticity, compared with stainless steel or a titanium alloy, has been used as a golf club material. For example, Japanese Utility Model Unexamined Publication No. Hei-1-72269 discloses a golf clubhead having a face portion defining a ball hitting surface of a head body, which portion is made by a beryllium copper material.
This golf clubhead, as shown in FIG. 5, includes a hollow metal head body 1 and a face portion 1a in the form of a thin face plate 3 made of a beryllium copper material attached to the hollow metal head body 1.
The aforementioned golf clubhead, however, has a structure in which the head body 1 is apt to be deformed at the time of hitting a golf ball since the head body 1 is constituted by a thin shell. Further, the face plate 3 is supported only by a marginal portion of the face portion 1a.
Therefore, in spite of using the beryllium material in the face plate 3, there arises the disadvantage that the characteristic high modulus of elasticity of beryllium causes deformation of the head body 1 at the time of the hitting of a ball, and thus the expected flight distance cannot be achieved.
Further, if the face plate 3 is made of pure beryllium in order to fully exhibit the advantage of the characteristic high modulus of elasticity, the face plate 3 is easily cracked or shattered since no consideration is given with respect to reducing the impact associated with the structure disclosed by the publication. The results of an experiment conducted by the present inventor shows that when a golf ball was hit with the golf clubhead having the disclosed structure, to which the pure beryllium face plate 3 of 3 mm thickness was attached, by an ordinary skilled gofer (the hitting impact is about 9800 Newtons), the pure beryllium face plate was shattered.